[NLRS] Do MAR-4s REALLY suck this bad?

[Donn Baker - WA2VOI/0]

Think about what the circuit looks like, Scott:  a 50ohm load in parallel with a 75 ohm load... only a portion of your 
output signal is actually going to the output.  Try a 1uH to 3uH choke in the Vcc line.  (A single bead won't have 
enough impedance)   I'd put the choke between the MAR-4 and the 75 ohm resistor, but it should work OK if its between 
the 75 ohm resistor and Vcc supply.  Bypass the choke on the Vcc side with a .1uF cap.  As for layout, try to get the 
choke (or resistor) to leave the circuit at right angles to the output trace.

73 Donn
WA2VOI/0

----- Original Message ----- 
From: "Scott" <acepilot at bloomer.net>
To: "NLRS List" <nlrs at mailman.qth.net>
Sent: Tuesday, November 18, 2008 3:16 PM
Subject: [NLRS] Do MAR-4s REALLY suck this bad?


>
>
> I added a MAR-4 to my to my TX IF (144 MHz) to get the drive up for my 10 GHz transverter.  I'm getting 5 dB gain at 
> 144 MHz.  Should be getting 8 dB or so.  I'm driving it with -7 dBm at 144 MHz. The DC supply is 9V through a 75 Ohm 
> resistor giving 5.25V at the output lead of the MAR-4 which is right on the money.  I slipped a ferrite bead on the 
> resistor lead on the MAR-4 side.  It's kinda big and lays on the circuit board trace over the output lead.  Could this 
> be "choking" the 144 output from the MAR-4?  I could actually build the choke with some #20 enameled wire to keep the 
> ferrite away from the trace...
>
> -- 
> Scott N0EDV
> http://corbenflyer.tripod.com/
> Flying Corben Junior Ace - Building RV-4
> Gotta Fly or Gonna Die
>
>
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